Batchelor etal
flame spray metallizing



C. S. BATCHELOR ET AL FLAME SPRAY METALLILING Original Filed Oct. 2, 1953 an m mu WW A mud

VAR

C m AW ow @EZSACQ July 29, 1969 United States Patent 0 19. 1967. Ser. No. for reissue Aug. 5,

8 Claims Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

I- :HIH'IRALT I)!" THE I'JISCLOSUHE Flume AfttllV routines on applied I v urn of a flurut' tprrrv rvr'r'r' rmrrprrir'd of u Htti'tllllt tzrht' filled with u l/rixotropic .vuipmidiut' nrrdr'um um tlittrtle particles 0/ t rrrrurt: nude our! curl r'di' modifying material.

This invention relates to the flame spraying of suhstrates \sith metallic coatings. to the novel method and means for accomplishing the same and to the novel products resulting therefrom.

More particularly, the present invention relates to the flame sprayinc of n stihstrate which may he a planar. angular or curvilinear base of heat-resistant character such as hodies of metallic. ceramic or mincral liher character. with a coating of metal of a new and improved character. and it i an ohject of the present invention to provide metal coatinrzs of the character aforesaid having inclusions of discrete particles 0t inorganic rnodityinu material di per ed therein.

In t}ClCl'til. the ohiects of the pre ent invention are accomplished by prosidinp novel composite llririte spray inc in: compo ed M a solid metal trilie huvinr. disposed therein discrete particles of inorrrrrnic modifying material disprrsed in ii suspending! medium siihstiiutially lllllttt: the confines til said tithe. the said su pending medium heinr: disrntcprzttile under [lame sprayirtrz conditions and tort coniitaritly aiding in providing a harrier against uhstari ti.il disintegration or said inoreunic material or suhstanliir alloying thereof Willi the luhc metal.

The composite llanie spraying wire of the present invention is adapted to he sprayed by conventional spray guns at a teriiperatiire and at a rate to atotui/e at least the solid metal title and to mechanically trap the rnodil'y' in; partL-le material inclusion without appreciahle alloy lug oi the solid metal component of the wire with the aforesaid modifyine tiller particle material or uppreciahle degradation of the latter.

lt is presently known to employ niuues and to provide composite deposits of materials such as. for example. ceramics and metallic materials by separately llariie spraying: the metal from a solid wire vrith the conventional vrire. flame spray or lltCtZlllllit'tll gun. and at the same time sprityinc the ceramic particle material lrrrrii a ditlcrcnt point and Ill an angle to the tlurnc prayed from a powder gun. In such operation the metal and the eparately sprayed particle material are [lll lL'LlCtl adjacent to each other and not in admixtures except possihly in the overlapping areas of the sprayed cones rcsiiltlnu from the flame spraying technique.

As distinr urshcd trorn the prior practices and when employing the composite flame spraying wire of the present invention. greater elliciencies are ohtained. that is. loss of sprayed metal and particularly loss of the muddying material. is materially reduced and more uniform mixflame spraying tee h- Ill till

Re. 25,534 Reissued July 29, 1959 tines are ()ldtll'lLtl. Employment of the present composite tiihes is particularly advantageous when employing particle iirirterial such as ceramics or graphite of lower gravity or finely divided particles of any gravity within the metal tube and which normally tend to disperse on spraying.

in the present case with the spray having a surrounding coating or conical zone of metallic particles result ing from the metal tube of the composite wire, and wherein the modifying particles disposed within the tube tends to be retained within said zone and adjacent the axis of the spray. their application onto the sprayed surlzice tends to he more confined. with the lesser volume of tiller particles tending to become overlayed with the metal of the tiihe. l hus vrith the employment of the composite lliime praying wire of the present invention better and truer mixtures are obtained in :in easy and more positive manner as distinguished from layers. since even when prayinr two materials simultaneously at an angle to each other it is dill'icult to have hoth meet. and one component tends to hi0 the other away. resulting in ysiistage. This is distinguished from the practice of the present invention in which use of the composite wire provides an enveloping and trap-like spray of metal formed from the tuhe around the sprayed particle material resulting from that disposed within the hollow of the eomposite llame spraying wire of the present invention.

Moreover. employment of conventional spray guns can he operated at a controlled feed rate and temperature such as to melt and atoniize the metal tube. the flame and feed rate l cing regulated so as to he insufhcient to apprceiahly degrade the contained modifying particle materials or to siihstantially lluy them with or dissolve them in the metal of the tithe.

The provision ot the composite llarne Spraying wire of the present invention. wherein the enveloping trrhe ifi composed of solid metal is particularly c nducive to the production of dcnsifierl deposits [IQ distinguished from the relatively porous character of the depo its renultine lrrrrn the tlame sprasiuy of solid metal tithes. This is he iitwed to result from the tact that the heat generated at lhc nor/h of the spray sun goes through the wall of the tithe rapidly as distinguished horn the requirement to travel through it. solid rod. and results in u more uniform distiihuriorr ot the heart into and through the metal tul e. Moreover. this metal which is atomized and propelled by gas under pressure at sttl' slirltlltllly the .same time that it is melted. due o its having: heen unitormly heated. apparently has a more plastic flow when the particles therein" land on the .sul stt'ttlc enabling these sprayed parllclc; to hectrnie deposited in a dense even. though nieehanically intcrloclcd. mass of particles and to provide hettcr anchoring and interlock of the contained modifying particle material uhich is simultaneously deposited. hi the flame spraying operation. the composite tuhe ot' the present invention is caused to protrude roughly ahoul r inch beyond the nozzle 'l his initially shields the lillers except those in actual physical contact with the tuhe. 'lhc fillers near the center of the tuhe are protected initially hy the suspendinc medium from rapid heating. Alter the tuhe ha melted auay the tillers and the sus pending material are sul'rlected to heat hut for extremely .short periods of time. This is adequate to rapidly disintegrate the carrier or suspending medium for the modifying particles material and to melt or pliisticile an appreciahle portion of the filler particle materials which are siisccptihlc to melting or plasticization at the term pcratrire of the generated heat or flame of the spray gun Consistent with insulation thereof by the tuhe per se and the insulating eticct of the suspending medium, as well as the cllcct of vaporization or heat disintegration of the latter.

The tube component of the composite ire of the pres' ent invention may be composed of metal .such as principally of copper. aluminum, or iron. the latter including steel. The inorganic tiller particles are selected principally to reinforce or otheriiise modify the tube metal by providing a sprayed composite deposit of the metals with improved properties such as improved real or apparent hardness. improved wearing characteristics and corrosion resistance. In such instances the fillers are generally of higher melting point and greater hardness than the metal tube although the inorganic fillers may in other instances be of lubricating character used either alone or in combination with the relatively hard fillers when it is desired to provide lubricating properties. In general the fillers are such that under the flame spraying conditions they do not substantially dissolve in or alloy with the tube metal nor become substantially degraded.

Moreover. the tube metal should generally comprise at least 50% and preferably 60% and upwards of the volume of the sprayed deposit so that the deposit is essentially composed of a matrix or the metal of the tube with modifying inclusions of the tiller material.

'lhe term inorgtiriic" as employed herein with refer ence to the filler materials vsill be understood to include broadly natural or synthetic minerals as well its metals and their alloys, and thus although the aforesaid relati\cly hard. high melting particle material inclusion can be iclractory ositlc particles such as alumina. Iir'conia. litania. beryllii, and the like. other particles such as a lelii par. inulli'rc. tungsten carbide. silicon carbide and the like can al o be employed. Likcui c. particles of metal may alo be employed such as nickel. chilled iron. steel. Lltlitll and the like.

Uihcrs which can be l.l\l;tl either alone or in coiirbirtitiiiri ith the tot'cgo rig to serte as lubricants or tiictioii motht li'l d igcnt and he like are graphite. lead, molybde "illll tllslll llltl c. ll..b "itt nrctals. lead-tit oldqi and the like.

tltlicr type of inorganic particles may be of composite character such as zinc. aluminum. copper and the like coated particle of graphite to sent: to prevent ovidation iii the graphite.

llze c inorganic particle material are generally emplo ed in sizes of from about 40 to about tititl mesh. larger than Jtt mesh causes particles to bounce away in praying re ulting in poor efficiency and unde irable poro ity. Particle of maller than about but) mesh such as those of colloidal size ithile useful in some instances are generally unde irable in that they cause loss of elliciency and degradation in flame praying.

Houevcr. the use of composite tubes with fillers of the character afore aid in flame spraying permits the incitiltlli ot metals and other inorganics that would normally alloy or decompose but because of the short time the hilt-i material is exposed to the flame a minimum amount tit alloying or degradation takes place.

'I he substrates may be components of triction mating urfaces uch as lly -ihecls. pressure plates. brake drums. tented and lll'lvtZlllCtl brake discs. brake drums for band brakes and the like. which may be composed of tcrrous materials such as iron or steel. copper. aluminum. or in the case of sttclt materials as brake bands the substrate may be felted or ivoven fibrous asbestos.

lhc-c friction rntterial substrates. in accordance with the pre ent iriiention. are preferably sprayed \tith composite t'lanie praying ire of the present invention to provide friction material overlays composed principally of copper uch as copper of )til. or higher purity with modifying inclusions to provide increase in effective hardnc s and re istance to abrasion and plastic flow of the copper. and thus provide wear-resistant surfaces without necessity for liquid cooling. At the same time there is lllltlillll/iltg of scoring and plasticizing of the copper metal and its mating urface. while obtaining and rctainin the high heat conductivity of the copper. The metal-particle .ill

till

material inclusion is such as to avoid substantial alloying uhich might reduce the heat conducting properties of the copper.

'l he use of copper tubing having reinforcing particle inclusion therein is also desirable in the electrical llClLl here high heat and electrical conductivity with improved near is desired for the mating parts such as in commututors and other rotating electrical parts. In such instances the substrates may be ferrous metal, aluminum, copper or ceramics.

Tubes of ferrous material such as for example austenitic steel containing hardening particles such as tungsten carbide. or reinforcing particles such as alumina, zireonia. mullite or the like may be employed for providing metallic substrates such as shafts or other surfaces with tough. near-resistant qualities. On the other hand. the inclusion in the various tubes can be of materials such as particles of copper, lead and the like to improve machining properties.

Composite ire wherein the tube component is of aluminum may be employed in the production of bearings, friction mating members and the like. Aluminum per se is notorious for gzilling. but in accordance with the present invention there can be readily included therein a rclatncly hard reinforcing particle material as aforesaid. to render aluminum suitable for friction material overlays and used in brakes. LllllLhLs and the like. ()tlier instances uhere use ol Zlllllllllllllll composites of the present in\cntion are ieasible is in beatings and bearing surfaces where the inclusion is it lubricant material such as graphite. making it suitable for such uses as cylinder liners and the like. making use ol sprayed aliiminiint tt-asible uithout l/inc.

Althou h in general it is pielcr'ted to use the tribe lllitlt lltll or substantially pure character and to prevent allot lug tlicrcol \i'ith the contained modifying tiller particle llt.lli. rial. in ome in tances tubes composcd or alloyed lllL'lltl may be employed in the production of beatings oi till Proved Properties. lltll\. tubes of brass or bronze such as pho phor bronze. yellow brass. Muntz metal and the like alloy may be ellectiicly employed for the tube compo item of the composite flame praying ire ot the present invention incorporating therein lubricating particle tiller iiititcriiils such as graphite. molybdenum disulphide, Bab-- bitt metal. and the like. lhc manufacture of such bearings has in the past been limited to expensiw and complicated iutcring processes employing sintci'ing technology and has precluded the use ot many lubricating materials such as tho e aforesaid.

lhc coti'iposite llanie spraying wire of the pre ent itiicntion in particularly adapted to facilitate the production of bearing suilaccs ol the aloiesaid character and other metallic overlays herein the inclusions are of loner niclting character than the tube or are unstable orn p unds at the itltltl titltltl" l. temperatures generated by the toy-acetylene or other chemical flame til the spray unit. in that lastly the tillers are protected by the metallic sheath. and secondly by the material in uhich tlic tillers are suspended and iiliicli pioiitles protective atmospheres bv disintegration or dissipation by evaporation til the tilUlCHlltl suspcndinc media. Moreover. of course control i bad by varying the inside and outside diaiiictcis of the tribe. the mesh size particles of the llllcts and their oit;in tity.

Thus in flame spraying, the metallic lube melts fir t and is atomi/ed and hurled at the target piece or sttl trate along \titli the filler matrcial \ihich has been protected tioni the heat by both the outer shield of the metal tube and the embracing suspending medium for the particles.

lhe method ol the present invention thus also permits the inclusion of metals which might normally alloy with th tube metal but because of the short time that the filler material. even when it is metal, is exposed to the lltone. little or no alloying ill take place.

As previously indicated a characterizing feature of the present invention resides in suspending the inorganic modifying filler particle material in a suspending medium which is of aqueous or organic character or mixed character and which is readily disintegrable under conditions of llaure spraying so that the particles while partially shielded are readily released under the influence of the flame and propelling gas. The employment of the suspending medium permits control of the amount of additive material in a precise manner and provides a means of keeping fillers of different gravity in uniform suspension and distribution within the hollow metal outer tube.

In one specific embodiment the suspension should he pumpable so that the metal tube may be filled by projecting the purnpable suspension into the tube by pressure or suction or a combination of both. and as an aid to this the tube may be first flushed with a conventional wetting agent. or in the alternative the pumpable suspension may include the wetting agent such as for example ethylene glycol or Aerosol OT (dioctyl sodium sulfo uccinate).

Thus, for example, as an aid to incorporating the particle material a slurry is first formed with water containing colloidal alumina vshich sets up to a thixotropic condition on standing. After filling a suitable length of tube the ends are scaled up for storage and use.

Other aids in forming thickened stable suspensions of modifying particle materials may be cereal starch pastes, and thickening agents such as aqueous sodium cnrboxy methyl cellulose, bentonite. vegetable gums and factices. Others are organic materials such as oils and greases having viscosities which may approach that of petroleum jelly. Other organic suspending media can be aqueous dispersions or solvent solutions of plastics such as of vinyl resins, butadienc-styrene or like synthetic rubbers. and the like. Uther types of organic su pending agents which may be employed are polyurethane and the like resins vhich may be foamed in place. Others are li'eitllrardenable resins such viscous epoxy resins, aqueous phenol-tormrildehydc resins and the like. These may be of a type which harden on standing or hardening may be accelerated by heating of the tube after the thermosetting resins are injected into the tube with their suspension of fillers.

Another type of suitable suspending agent which is not of the iluid or ptrmprible character are extruded mixes of rubber compositions containing the iiller particles such as may be made in a llanbury or dough mixer, or the like and extruded through a suitable nozzle to selt susttrirv ing form and to a diameter which can be readily threaded into the metal tube. When a mix of this or similar nature is hardened the metal tube may be formed of a sheet of metal and rolled or shaped about the filler.

Vhcn the suspending medium contains llqltCOtts runtcrials the water of course readily vaporizes during the flame spraying and prositles a cooling atmosphere to limit destruction or alloying during the small increment of time the composite Wire is subjected to the flame of the spray gun. and the same applies to the degradation products of the organics which in general additionally provide a protective non-oxidizing atmosphere and which readily carbonize. These rapidly free the compound or suspended modifying particle materials from suspension within the tube which of course is simultaneously subjected to atomization by the heat and propelling gases of the spray gun.

in all instances due to the flame spraying technique employed and the protection and rapid cooling of the particle material on leaving the gun in its passage to the substrate, no appreciable alloying is encountered and the irtlelity of both the metal and the contained particle material is substantially retained.

in tire acromparryiog drawings,

l lt). l diagranirrratically indicates the spraying of a composite tlame spraying wire of the present invention onto a llltl substrate.

till

till

Til

llti. I is a longitudinal \Lcllt tI oi the composite llante spraying viir'e of the present invention.

FIG. 3 is a relatively enlarged view of the end of the nozzle of the tlame spraying gun and of the composite ire as it issues therefrom as it is atomized, illustrating the cmcloping conical effect of the outer cone of atomized metal and the inwardly disposed issuing cone of disseminated modifying particle material inclusion.

Thus referring to the drawings, the flame spraying wire 10 of the present invention comprises a metal tube or jacket 1] which can have an outside diameter of l ir inch to fit a standard wirc flame spraying gun and suitably has an inside diameter of about ,1 inch filled with a suspension of adjuvant or modifying particle material 12. Spraying of the composite wire 10 which desirably is flexible and fed from a conventional reel, not shown. is diagrammatically shown in FIG. 1 by means of the nozzle generally indicated as 13 having an air cap 14 together with pa sages therein comprising the compressed air passage 15 between the air cap 14 and the nozzle part 16. The combustion gas 18 passes between the nozzle parts 16 and 17 which provides an axial orifice for supporting the composite wire 10 while being fed through the nozzle. The sources of combustion gases and compressible propelling gas, i.e. the air supply being part of conventional metallizing guns is well understood and therefore not shown.

The resulting atomized spray 19 initially comprising an outer cone 20 and an inner cone 21 impinges at a right angle to the substrate 22 with high velocity and efilciency and with a better and truer mix than when sep arately spraying particle material and metal rod at angles converging to the work. In the latter practice one spray tends to blow the other away, whereas in the present. method and with our novel composite wire, an envelop mg trap-like spray of metal envelops the contained particle material to provide a high and stable yield and a substantially homogeneous mixed surface coating 23, as distinguished from layers of the components. Although the substrate 22 is shown to be tlat it will be under tood that it may be curvilinear for parts such as bearings. brake shoes, brake drums, shafts and other curvilinear or cylindrical surfaces, and with such curvilinear surfaces it ill be understood that the spray is to be in a general radial direction to the \sorit, such radial projection being generally comprehended h the terminology in the [ob lowing claims and being in a direction normal to the tsork.

it ill be understood of course that when spraying metallic substrates, they are conventionally prcheated hetore spraying, suitably cleaned or abraded and if desired sprayed with an underlay or flash of a spray metal or alloy. such as for example low melting silver solder or silver brazing alloy. as an aid in anchoring the deposit. The resulting sprayed or overlaid substrate may be suitably heated to from about i200 to about d" F. to improve both the bond and strength of the composite as is well understood in the flame spraying or metallizing art.

As an example of the practice of the present invention and for the purpose of illustration and not limitation, a substantially pure copper tubing of the dimensions aforesaid was liilcd with an aqueous slurry of colloidal alumina and our) me h crystalline aluminum oxide nhich had set up to a thisotropic character. The ultimate analysis of the tube as t ed into the gun was 93) copper. 2) aluminum O\itlc. 4",? (will) mesh alumina, and I'l by weight of water (equivalent respectively to 80.2%. 4.1% litlfi, and 7.7? by volume). This was sprayed from .r conventional tlaore spray gun using an oxyacetylene tlame onto an aluminum brake drum. An analysis of the deposit of metal showed )5'6 copper and 5'1 aluminum by weight. 'llie alumina particle rrruterial was extrcineli vvcll dispersed as observed under a microscope, the copper was extremely dense and on the lirrished machined surface the alumina was almost invisible.

innit A typical formula of a tiller particle material u pen- .siun is one compound of 4 parts by weight of colloidal alumina (Du Punt Baymal). ll parts" of hill] mesh Alundum. and 5 part or le-s of .1 er, lh: Alundum and colloidal aiumina are pre-nuxed dry and then added to the 1116? while agitating The mixture i allowed to age for 12 hours and then re-agitated. The product is a paintlike thixotropic liquid and Can readily he pumped into a metal tube.

in lieu ut the Alundum equivalent mesh grades t l lltit refractory or abrasive materials uch as electric :lly iuscd Yirconia, mullite. emery. silica and the like may he cutplnyed. in lieu of the colloidal alumina sodium carb n; methyl cellulose, benltinite china city. and the l l thiekening agents may be employed as the u ptliduuz media as previously de cribed 'lhus for ctample. a lubricant unit su pension ni l-c hunted h eight of 2 part eraplrite. 74 part water it) part sodium L' tll lk) mcthylcellulu e and It part or Aerosol Ul. these are mixed and permitted to stand for 12 hours and then re'agittited to re ult in a paint like liquid. A rrri\ imilar to the lort'gou t: but employing F t parts of water and 5H parts by weight of graphite reults in it suspension tuning a thixotropic lil-te chamcter.

Another uitable {Tllt is, one containing part hy weight of the foliuwing: siiser ponder fiitt Ztttl mesh tungsten carbide powder 541i, sodium ctrll' t t} methylcellulosc Il and water 3 The u ual length of tai ing i approximately 50 feet and the out ide diameter suitable for the flame prav gun is s inch '1 he all Ihicl.nes of the tuhe Can be as desired and uitable can l e on the order 0t trout about vt lt in about Hill An abrasire resisting steel oserlii t for material ub ject to high unit pre ure and sliding stich a clawed iLulway track and tor the linger of power lroscl jeetcd to huclt and horn abra ion is a tube composed of an austcnitit' mangttne e alloy EtJHtFt' Ltl or l't tailOl'l. .1: manganese u I" \lltCUfl t inut ttirn h;- ACtjJlIL lrarlne in outside ilrtuittter' t t inch .inti in Inside diameter in inch Ilris is tilled with ll iwtroprc ll'llt tontirininr: it l me h Alunduru and an aqueous rliwper utn coiloidal alumina to pinrrde 4m llil llillk' ltll.|l\s)s wt in, .iustcnuie llltlnc' tllLWC teel and l Alundttur When sprayed (mm a uhstrate as a out, rll lL'l tlcanin and flash coating with molybdenum. a prayed depo it or nlirltl. 14" teel and Vi by twig-lit oi Muudum is turned the incorporated ruirtlcle Ill 'sliurtlirn c' illil may to wear l'C WJFiMJ and reduction of pla tu; lltnt.

It r'stil be apparent from the foregoing: that hy' means of the nosel compo ite wire hereinabose described one can at one time trunt a single so uce and in a motel and LlllLlLl'll manner coat a substrate with a matrix ol metal or desired character which may he rihstantially pure or a predeterrrtined alloy. and while suhstantiall reuinin; the character of the .dnre ttid metal or alloy. incorporate therein Lt uhstanttallt distontinutnr tilltr or inclu ion HitlLl'l can he one \ihich i nt reiatitcly hard and l'ugh me lint: point wherein the ellettiie hardne re istance to alu'a inn and plastic flow oi the metal is uni e-reed prmidtng; \ieanreststant urlates l-l L'l,ll. ltu crrrnpie in both the friction eiernents and mating lltttti" lltls til friction couples uch as l ralms and clutche electrical parts or other wearing", sullicu Armin the dis cuurinuo r ltlltr or irLllisiori may l e t t a lubricating nature thin ltl |iItt-ltlt hearing surtatcs ill enhanced Lllltl" l tter or pr rrrtir use ol lui' ritartt metal ruth as aluminum in l LHtlHlls ill i l now-l thtuatlcr, {\(Jnlll, various materials sutli as \ltil may hare inciiiporattwl tlurcuitli nirtitl lll tlttlllv tiluth enhar te utichinalultty and umult: in titwisrtl hurlnc and re islturte to wear sutli as lll tlte tase til liattand the like.

Illl

We Llairn:

IV The method t t coating a substrate with a metal uratris and an inorganic particle inclusion which comprises llame spraying .said substrate in a direction substantially normal thereto with composite llamc spraying wire comprised of a metallic tube and discrete particles of ceramic oxide and carbide modifying material dis persed in a thixotropic suspending medium sul stantially filling the confines oi said tube, said suspending medium being disintegrable under flame spraying conditions and concomitantly prosiding a barrier against substantial disintegration of said inorganic material or substantial alloyin; thereof with the tube metal.

2. 'llre method til coating it substrate \silh a metal inatris and an liltlltjltlll particle inclusion \ihich coinprr es l arne piayur said substrate in a direction suh titnrially normal thereto with eomposite llame spraying riirc uinipo ed of .I metallic tube and discrete ptu'titles oi teranrie nude and carbide rnodilyin material d|spersed in a tlnxotropic suspending medium sub tantiall lilling the conlines of said tube. said suspending medium being disinlegrahle under tlame spraying conditions and conctimitantiy providing a barrier against substantial disintegration of said inorganic material or substantiai alloying thereof with the tube metal,

3. A compo ite llanre spraying wire composed n! a metallic tube. and di crete particles of ceramic oxide and carbide modifying material dispersed in a [liquid] r/ulmrmpt'r u pending medium substantially titling the conlrnes of said tuhe. said su pending medium being disintegrable under flame spraying conditions and concomitant- 5y providing a barrier against substantial disintegration til aid inorganic material or substantial alloying; there of with the tube metal.

4. ('oruposite llama spraying wire composed of a metal lrc tube and discrete particles of ceramic oside and carlwdr' moditying material disper ed in a liquid suspend li L', medium substantially lililrtg the eonlines of said tube. will suspending rncdiuni heing: disinteerahle under Ilanic studying! tunditions and concomitantly prm iding a barrier aeainst substantial disintegration of said inorganic ma- [trial or substantially alloying thereof with the tribe metal 5. 'llte composite of claim 4 wherein the suspendiru: medium comprises aqueous material.

6. 'lhe composite of claim 4 wherein the suspendine: medium with its inorganic particle content is pumpttble 7. lhc touiposite of tlaim 4 which includes in additinn inorganic lnhricatine particle material lit lhe composite ol claim 4 \sherein said inurpante particles comprise particles of higher melting point and creatcr ltaldttess than said tube together with riuely di ided graphite References ('ited lhe l oiltmin z l'ertlctice cited hy the l\anunet. tire of ietord in the patented ltlc Hi this patent or tlic oriental patent A, tittl lAN. A istrtul l tiirniner 

